The season for operation of enclosed ice-skating rinks has been increasing the last few years such that the ice surfaces are maintained on a yearly basis or for a ten-month period excluding July and August. In many geographical areas in the spring, summer, and early fall months, high humidity conditions are encountered during the day. When the temperature drops at night, large quantities of moisture are condensed on the colder inner surfaces of the structure, such as the ceiling and ceiling beams resulting in corrosion. This requires time-consuming and costly maintenance procedures.
Attempts to overcome this problem have employed large-scale refrigeration or air-conditioning units. However, the use of a single unit has not proven satisfactory since the coil carrying the refrigerant would eventually ice up on its outer surfaces and the refrigeration unit would have to be shut down to allow the ice to melt off. Alternate refrigeration units have been considered, but this is a costly procedure. The use of air dehydrators is not feasible because of the cost and large volume of air to be handled.
The present invention is directed to a method and apparatus for inhibiting the formation of ice on the heat-exchange surfaces of an air-conditioning unit. The invention in one embodiment is directed to a method and apparatus for preventing the formation of ice on the cooling coil in a heat-exchange unit, which unit conditions an airstream by removing a portion of its moisture (water) content.
In the preferred embodiment of my invention, a cooling coil is disposed in a zone, which zone is maintained at a pressure higher than the pressure of the air introduced into the zone. This increased pressure raises the temperature of the air relative to its inlet temperature and also lowers the freezing point of the entrained moisture. The surface of the cooling coil is less than the dew point temperature of the airstream in the zone and more than the temperature at which the condensed moisture would exhibit a phase change from liquid (water) to solid (ice).
Stated otherwise, the coil surface temperatures are at a temperature lower than that of the air in the zone but still at a temperature above that at which ice would form and below the dew point temperature of the air contacting said surfaces. The air contacts the heat-exchange surface, is cooled, and moisture is condensed therefrom. The air is subsequently removed from the zone and experiences a pressure drop which lowers its temperature. In this application, dew point temperature is considered the temperature at which air is saturated with moisture.